Mobile phones are tested during manufacturing and in service depots to ensure ultimate quality control for fulfilling the necessary specifications for operating in the cellular network. As for manufacturing, such test measurements serve to determine when it is necessary to exchange defective components, to minimize manufacturing errors and to maintain quality control. Further, regarding end control, the test measurements serve for checking the basic functions and for the final trimming or alignment of the mobiles. Also, test measurements can assist in the search for defects in defective mobiles in a repair shop or checking basic functions in a dealer's shop. In order to conduct such quality measurements test equipment for carrying out RF tests is required, in particular so-called mobile testers.
In the prior art, for determining the transmission quality respective measurement values, characteristic of the relevant specifications, are taken in single frequency channels of a cellular telecommunication net or network. Measurements values comprise RF parameters such as power, frequency, phase/frequency error, burst behavior, time behavior and bit error rate for single communication channels of a network. The sampling of the relevant physical measurement values or parameters for characterizing the channel properties are considered to be important means or tools for determination of the RF parameters and, thus, for securing quality when manufacturing or servicing mobiles. The selection of several frequency channels serves for testing or checking whether the mobile or terminal or telecommunicator fulfills its specifications over the entire frequency range.
To this end, the frequency channels of the used frequency band (e.g., frequency channels f.sub.1, f.sub.2 and f.sub.3 shown in FIG. 1) are sequentially switched through, wherein a complete measurement of the respective frequency channel relating to measurement values such as power, frequency, phase, burst behavior, time behavior and bit error rate is taken before the measurement is switched to the next channel (see FIG. 2). That is, in the prior art these quality measurements are carried out sequentially for the single frequency channels. In each single frequency channel the entire or complete desired set of measurement values or RF parameters is sampled before it is switched over to the next frequency channel to start the measurement procedure anew.
The switching between the single frequency channels requires, at each and every time, the exchange of data packets or telegrams comprising command signals between the mobile tester and the mobile under test in order to adjust the mobile to the respective new frequency channel, also in particular with respect to exact point in time when the switching is intended to take place. In other words, in order to switch the mobile under test to the respective next frequency channel and to adjust it thereto, in particular regarding the timing and synchronization, there have to be intermittently exchanged protocol sequences comprising command signals between the mobile under test and the testing device (see FIG. 3). In summation, unwanted long measurement times are necessitated since command signals have to be exchanged between the mobile tester and the mobile and the necessary synchronization of the tester with the mobile for switching between the frequency channels with interweaved measurement cycles. On the one hand these long testing times are caused by the time a measurement takes and on the other hand by the command intervals. Thus, this process is very time consuming and needs much specialized software.
Regarding repair and service of mobiles, it is known to carry out adjustments or trimmings of components in these mobiles in order to optimize transmission quality. It is quite time consuming to determine the effect of such adjustments and trimmings for all parts of one or more frequency bands, in particular also within one band. Therefore, such a trimming is quite time consuming, costly and difficult to optimize.
Telecommunication systems or networks are known in the prior art which comprise a so-called frequency hopping technique. As an example, so-called GSM, i.e. Global System of Mobile communications, systems are known. With these systems during transmission operation of a mobile a digitized speech signal is transmitted using a frequency hopping technique using several frequency channels of a frequency band, wherein in a fraction of a second a switching occurs from one frequency channel to a next one. By using more than one frequency channel in a successive manner the transmission of information is less dependent on the transmission quality of a single frequency channel. Thereby, the frequency hopping ability of the GSM network serves for reducing the danger of interferences by using several frequency channels which are switched over from burst to burst in a particular order. The prior art is unsatisfactory in that the known measurement methods are time consuming and thereby costly.